THE FLOW OF WATER IN" WOOD-STAVE PIPE. 



91 



to flow, into the particular materials of whicli the pipes are constructed, except in 

 sharply limited cases where the material is a meas- 

 ure of the roughness. 



The writer considers the author's formula as good 

 and as safe as any, if its limitations as shown by 

 column 19, Table 2, be taken into account and if 

 the velocity in the pipe imder design is not much 

 greater than in the data presented in Table 2. 



This suggests the difficulty in getting the engineer- 

 ing public to recognize the average quality of an 

 averaging formula. Thus the significance of the 

 formulas on page 309, Trans. Amer. Soc. Civ. Engin., 

 vol. 51 (1903), is very liable to be overlooked when 

 presented in the form given on page 281, Eng. Rec, 

 September 3, 1904. 



Unless these general interrelations of all pipefloiu 

 data are specifically emphasized, it seems that a 

 good opportunity will be lost. The author states 

 on page 50, "However, in deriving the new for- 

 mula, tests made on round, wood-stave pipe only 

 were considered, in view of the proposed use of such 

 a formula. " The inference that data on other pipes 

 are not relevant will be drawn from this by the 

 great body of readers. Thus the error so long per- 

 petuated by hydraulic texts will be given apparent 

 sanction. 



From a pm'ely selfish viewpoint the writer would 

 not be eager to see the author's paper broadened as 

 suggested. It furnishes data to drive home matters 

 about which there have been great uncertainty in 

 the minds of a few, and general ignorance in the 

 minds of the many who place a halo about text- 

 book formulas. If the author does not, others will 

 do it. 



The value of the paper as it stands is great. It is 

 in the hope that the author may be persuaded to 

 make the shift in viewpoint necessary to add much 

 to the permanent value of his deductions that the 

 writer ventures these comments. 



In The Cornell Civil Engineer of December, 1911, >2S<.^i Iv^^ '/N/ S •^' 



page 127, there are some data that may be found of 

 interest in connection with the author's method of 

 finding velocities by injecting a colored solution into 

 the pipes and timing the interval from the instant 

 of injection to midway between the first and last 

 appearances of color downstream. 



Prof.Hoskins: The experimental work described 

 in "The Flow of Water in Wood-Stave Pipe" is a 

 valuable addition to knowledge on the subject, and 

 the author's summary of conclusions appears to 

 merit confidence as embodying present knowledge 

 on the hydraulics of wood-stave pipe. The expo- 

 nential formula adopted as the result of the discussion is probably as reliable a 



